The importance of cosmetically attractive, whitened or brightened, teeth in today's society cannot seriously be questioned. During the past ten years, there has been a virtual explosion of supposed new and improved processes for the simplification and efficacy of teeth whitening and brightening. However, each such process has had several drawbacks creating a negative impact on the user, including high costs of the new treatments, repeated visits to the dentist/cosmetician for repeated treatments, difficulty of use, length of time to achieve the desired results, and need for professional help.
The prior art has known many devices and methods for externally treating a tooth or teeth of a patient. The most primitive method of externally treating a tooth involved the direct application of an active agent to the tooth of the patient. Examples of the external treatment of a tooth include the direct application of active agents such as fluoride, tooth whiteners, antibiotics, antihistamines and topical anesthetics.
Although the external treatment of a tooth by the direct application of an active agent has achieved some success, several problems exist with this method. First, the direct application of an active agent is generally inefficient since the active agent can be applied to the surface of the tooth for only a relatively short period of time with only modest results. The relatively short period of time of application is determined by the length of time the active agent remains on the tooth of the patient. The length of time the active agent remains on the tooth of the patient is generally determined by the viscosity of the active agent and the ability of the active agent to remain on the tooth as well as the ability of the patient to remain immobile during the treatment.
In an effort to overcome these problems, some in the prior art have increased the concentration of the active agent in an effort to produce satisfactory results within the limited period of time permitted by the direct application of the active agent. Unfortunately, the increase in concentration of the active agent produces undesirable side effects for the patient.
Many other prior art treatment processes have also involved the direct application of a physical process to the external surface of a tooth to brighten same, involving, for example, the use of bonding to mask previously existing stains on the tooth, crowns or porcelain veneers physically attached to the tooth to in effect hide the stains, or application of high physical heat through the past use of a modified soldering iron, a heat lamp or today's equivalent, a laser. However, all of these applications involved the direct need for a professional doctor and/or dentist chair time and the resulting associated costs. The user has had little control over the process being applied to his teeth, and had to frequently revisit his doctor/dentist for follow-up application and treatments.
The remaining treatment processes have tried to give the user some sort of control over the bleaching and whitening process, but usually at the expense of time and efficiency, and with varying results. For example, others in the prior art have utilized a plastic splint or stint molded to overlay the teeth of the patient in an effort to retain a tooth whitening agent in contact with the teeth of the patient over an extended period of time. Such a method is set forth in an article entitled "Nightguard Vital Bleaching" which has been published in Quintessence International, Volume 20, March, 1989. In this method, a stint is molded to fit the entire upper or lower teeth of the patient and to seal with the gingiva of the patient. The active agent is introduced into the stint and the stint is inserted upon the teeth of the patient to retain the active agent in close contact with the teeth of the patient.
Although the use of a plastic stint allowed the active agent to remain in contact with the teeth for an extended period of time, the use of the plastic stint had certain disadvantages. First, since the plastic stint was molded to intimately fit with the entire upper or lower teeth of the patient, the stint was uncomfortable due to the tightness of the fit with the teeth. Second, the stint sealed with the gingiva of the patient, making the stint incapable of fitting with a single tooth or just several teeth. Third, the stint had to be cut back adjacent to the gingival margin to prevent undesired deterioration of the gingiva due to the intimate contact of the stint with the gingiva during the treatment process. Forth, the intimate fit of the stint with the entire upper or lower teeth of the patient prevented ingress and egress of oxygen to the internal regions of the stint. Fifth, the intimate fit of the stint with the entire upper or lower teeth of the patient made the stint difficult to remove in some instances. Sixth, notwithstanding the intimate region of the stint with the entire upper or lower teeth of the patient, the active agent within the internal region of the stint would over time migrate from the stint, thus reducing the effectiveness of the active agent upon the teeth.
The liquid splints/stints utilized by the Munro patent, U.S. Pat. No. RE 34,196, the disclosure of which is hereby incorporated by reference, constituted a great advance in the art at the time and did permit some freedom of use by the user. However, the splints still required several hours of use of the liquid splint per day for many days to achieve the desired brightening effects, and were uncomfortable to some due to their tightness over the teeth. There was also a problem involving the retention of the brightening agent on the treated teeth. Several inventions followed which attempted to resolve the problems of the whitening agent being swallowed, dissolved/weakened by saliva, or leaking out of the splint onto the gums/gingiva or labia. Several other new processes were introduced which addressed the retention of whitening agent through the additions of a retaining material/reservoir (U.S. Pat. No. 4,968,251) and plurality of indentations/baffles to prevent the loss of the whitening agent (U.S. Pat. No. 5,575,655). However, these later inventions/processes did not sufficiently address the time and efficiency issues of the user, though they did allow the user more freedom in his control over the bleaching process.
In the effort to reduce the time needed for the bleaching process, some in the prior art have tried to increase the concentration and/or the viscosity of the whitening agent (see, e.g. Fischer U.S. Pat. No. 5,098,303), thereby hoping to speed up the brightening process while lowering the time the user had to use the splint of Munro or later modified and improved versions of same. However, the increased concentration and/or viscosity of the brightening agent--frequently a peroxide derivative--resulted in an accompanying increase in deleterious side effects for the user. To avoid tissue damage from the increased concentration of the brightening agent, the user had to frequently shorten his exposure to same with intervening periods of no exposure--with the result that the overall bleaching time (time to achieve whitened/brightened teeth) has remained more or less similar.
There have been additional techniques and devices developed over the years in an effort to improve the methods for brightening or whitening teeth. One such effort was the application of heat to dental and/or periodontal structures and the whitening agents, such as peroxides, being applied thereto. It is widely known in the art that heat activates peroxide solutions, increasing their effectiveness as whitening agents. Under the "Q10 Rule," it is well known in the art that an increase of 10.degree. C. in temperature of whitening agents/solutions--such as peroxides and peroxide derivatives--doubles the speed of the whitening action/process. In other words, the time to achieve whitening results is effectively halved. Thus, whitening time can be reduced by 50% by application of a sufficient supra-body heat temperature to the whitening agent.
For this reason, the application of heat to dental and/or periodontal structures and the whitening agents has long been a desired treatment parameter, but the lack of control of the amount of heat or the difficulty associated with the delivery of a therapeutic quantity of heat for sufficient time to be useful along with the degree of discomfort to the patient has limited the use of heat in various dental/periodontal treatments. For example, in an article entitled "Bleaching Tetracycline-Stained Vital Teeth" published in Oral Surg., March 1970, a method was introduced to bleach certain stained teeth by the application of 30% hydrogen peroxide (Super oxol) to individual teeth warmed or heated by a modified soldering iron (bleaching tool) to the individual's limit for pain (pain threshold), for a period of 30 minutes over 8 treatments, spanning a two-month period. All treatments had to be conducted in the dentist's office, with follow-up visits to maintain bleaching monthly thereafter. The inventors noted that this bleaching technique would be contra indicated for any tooth bearing a silicate/resin restoration. Interestingly, the pulp temperature remained constant and unchanged during treatment.
With the advent of Munro, the slight advantages offered by the prior art heating source method--and its progeny--were overcome, as the tray technology of Munro and its progeny achieved equivalent teeth whitening results by longer exposure times to peroxide activated by body heat. The art tried to counter the Munro progeny trays with better sources of heat and peroxides to counter the relative ease of the Munro trays with better whitening results. Photo flood lights, hot irons (soldering irons), hot water baths and lasers have all been recorded in the art as methods of activating, and heating, peroxide compounds for teeth whitening procedures. With the exception of some of the hot water bath techniques, all of these heating methods must be practiced by a dentist or other medical professional in the office due to the cumbersome and non-portable natures of these heat sources; these methods are not at home techniques. As a result, office procedures are costly on a per hour basis, especially when many hours of treatment may be necessary over an extended number of days. Thus, in an effort to maximize results within short time periods, therefore decreasing "chair time" at the dental office, high concentrations of whitening solutions (peroxide compounds) have been required in addition to uncomfortably high levels of heat.
In a typical tray-type whitening method utilizing Munro and its progeny, a tray is loaded with carbamide peroxide, or other similar bleaching/whitening agent, and placed over the teeth to be whitened. The tray is then left in contact with the teeth for a prescribed period of time, during which time some whitening or bleaching of the tooth/teeth occurs. Repeated applications are necessary as whitening of the tooth/teeth occurs in small increments over a period of several weeks. The degree of whitening is dependent, in part, on the amount and concentration of the whitening solution and the time in which said solution remains in contact with the teeth, as well as the susceptibility of the tooth to this whitening procedure.
The only remaining variable is the temperature under which the bleaching/whitening action takes place. Currently, in all tray-type whitening methods, the bleaching/whitening takes place at body temperature (inside of the mouth), though some methods perform a preliminary step of warming the whitening agent (by immersing same into a bowl of warm water) to obtain a temporary body-like or greater temperature before the placement of the whitening agent within the tray. However, no current tray-type method utilizes sustained supra-body heat temperature, and the constant maintenance of same, on the whitening agent during the whitening/bleaching process. This problem is further exemplified and exacerbated due to the user's/patient's mouth being open during use of the tray; the inhale/exhale process brings room temperature air over the teeth constantly. Thus, simple breathing thereby lowers the temperature of the whitening agent and thus lowers the reaction speed, thereby increasing the total time needed for the user to obtain whitened teeth.
Therefore, there is a need in the art for a simplified and less costly process of tooth brightening that the user can do, either at home or during a single trip or two to the dentist/doctor's office, without the serious side effects associated with an increase in the concentration of the whitening agent. A further need exists in the art for a simplified process of tooth brightening associated with a maintenance system for the now whitened/brightened teeth, said process being within the total control and ability of the user.